QT5 and SQLite3 "No query Unable to fetch row"

Question

i have a problem with my SQLite Database in QT5. I have table called "mytable" and im trying to save, change or load data there. The table looks like this (CODE):

"mytable" ("id" INTEGER PRIMARY KEY  NOT NULL , "name" VARCHAR NOT NULL , "akcie" INTEGER NOT NULL )

Then im trying to work with this database like this (CODE):

void MainWindow::on_pushButton_save_clicked()
{
    QString jmeno, IDcko, ak;

    IDcko = ui->lineEdit_ID->text();
    jmeno = ui->lineEdit_Name->text();
    ak = ui->lineEdit_Akcie->text();

    open_connection();

    QSqlQuery query;
    query.prepare("INSERT INTO mytable(id, name, akcie) VALUES(id= \'"+ IDcko +"\', name= \'"+ jmeno +"\', akcie= \'"+ ak +"\')");

    if(query.exec())
    {
        QMessageBox::information(this, tr("SAVED"), tr("Some text."));
        close_connection();
    }
    else
    {
        QMessageBox::critical(this, tr("NOT SAVED"), query.lastError().text());
        qDebug() << query.lastError().text();
    }
}

In the same file im opening connection like this (CODE):

bool MainWindow::open_connection()
{
    QSqlDatabase database;
    database = QSqlDatabase::addDatabase("QSQLITE");
    database.setDatabaseName("‪..\\added\\test_table.sqlite");
    if(!database.open())
    {
        qDebug() << "not opened connection";
        return false;
    }
    else
    {
        qDebug() << "opened connection";
        return true;
    }
}

And im still getting error: "No query Unable to fetch row", i have been looking for the answer really hard but nothing worked. Could it be because of some includes or am I doing something wrong?

Thank you in advance for your help!

What does QSqlQuery::lastError() say?

cmannett85
– cmannett85

2015-07-11 15:25:34 +00:00
Commented Jul 11, 2015 at 15:25 — cmannett85
– cmannett85, Commented Jul 11, 2015 at 15:25
@cmannett85 It still says: "No query Unable to fetch row"

Petr Bečka
– Petr Bečka

2015-07-12 11:04:26 +00:00
Commented Jul 12, 2015 at 11:04 — Petr Bečka
– Petr Bečka, Commented Jul 12, 2015 at 11:04

Miki · Accepted Answer · 2015-07-12 11:30:15Z

3

You are not preparing the query right. Use bindings like:

query.prepare("INSERT INTO mytable(id, name, akcie) VALUES(:id, :name, :akcie)");
query.bindValue(":id", IDcko);
query.bindValue(":name", jmeno);
query.bindValue(":akcie", ak);

edited Jul 12, 2015 at 11:30

answered Jul 11, 2015 at 13:23

Miki

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8 Comments

Miki Over a year ago

print out the query you are preparing with query.executedQuery()

cmannett85 Over a year ago

@PetrBečka you should use bindings as much as possible anyway to prevent SQL injection attacks.

Petr Bečka Over a year ago

@Miki query.executedQuery() shows me this: "INSERT INTO mytable(id, name, akcie) VALUES(id= 'idcko', name= 'jm', akcie= 'akc')" and I am using bindValues as you told me..

Miki Over a year ago

remove the (') from the prepare.... that should work.. sorry for the typo. Aslo remove (id=). See update code in the answer

Petr Bečka Over a year ago

@Miki Ok, something has changed, my query.prepare() looks exactly like yours and im getting query.lastError() like: " Parameter count mismatch" and my query.executedQuery() is saying: "INSERT INTO mytable(id, name, akcie) VALUES(?, ?, ?)"

|

Sardorbek Khujaev · Accepted Answer · 2020-03-02 08:54:01Z

0

You did not execute the query. You should use bindings like:

query.prepare("INSERT INTO mytable(id, name, akcie) VALUES(?, ?, ?)");
query.addBindValue(IDcko);
query.addBindValue(jmeno);
query.addBindValue(ak); 
query.exec();

or, like @Miki mentioned, with the help of query.bindValue(":id", IDCko) function. The last way will be to write the query text straightly (without the need to separately call query.exec():

query("INSERT INTO mytable(id, name, akcie) VALUES(id= \'"+ IDcko +"\', name= \'"+ jmeno +"\', akcie= \'"+ ak +"\')");

answered Mar 2, 2020 at 8:54

Sardorbek Khujaev

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